Water treatment strategies commonly employ polymers for purification of industrial water systems. Fluorescent tagged polymers are often chosen as treatment chemicals because fluorescence can be used to monitor both concentration and location of the polymer or a substance associated with the polymer. A small quantity of fluorescent dye can be attached to the polymer and the fluorescence of the tagged polymer measured using conventional fluorescence detection equipment. Real time fluorescent methods can be used to rapidly adjust treatment dosage based on the measured performance of the water system. There are a number of fluorescent water treatment options available, but many existing treatment polymers and methods have certain disadvantages.
Wastewater can exhibit large background fluorescence due to the presence of naturally occurring organic and inorganic compounds, making it difficult to differentiate the fluorescent signal of the tagged polymer from the signal of the naturally occurring fluorescing particles in the wastewater. The fluorescence region of wastewater background is generally less than 550 nm, which overlaps with the fluorescence emission region of many commonly used fluorescent dyes. Thus, the development of a fluorescent tag and fluorescent tagged polymer that has a fluorescence emission range at a wavelength greater than 550 nm would be particularly beneficial.
However, the synthesis of fluorescent tagged polymers is commonly problematic because polymerization can occur with incomplete incorporation of fluorescent tag into the treatment polymer. Incorporation of the fluorescent monomer tag into the treatment polymer can be poor due to side reactions such as self polymerization and is often dependent upon the relative reactivity of the reaction monomers. Incomplete incorporation of the fluorescent tag into the treatment polymer can lead to additional chemical waste and polymer characterization challenges. Thus, there is a need for novel fluorescent monomers that will polymerize with high incorporation of the monomer into treatment polymers.
Moreover, fluorescence intensity of tagged polymers can vary if the polymer is susceptible to decomposition under certain pH conditions. For example, some polymers undergo cleavage of the fluorescent portion of the molecule due to acid- or base-catalyzed hydrolysis, resulting in unreliable fluorescence intensity measurements. Wastewater pH can vary based on the organic and inorganic substances present in the wastewater, which can range from highly acidic to highly basic. Thus, a fluorescent tag and fluorescent tagged polymer for wastewater treatment should have good stability under a range of pH conditions.
Accordingly, there is a need for improved fluorescent tags and improved fluorescent tagged polymers that can be used in tracing treatment chemicals in wastewater.